Fluid aid for needling

ABSTRACT

A highly needled fabric is produced by treating fabric, e.g., a needled fabric having a density of at least 8 pounds per cubic foot, with a needling fluid and then needling to increase the density, e.g., to at least 12 pounds per cubic foot. The needling fluid is preferably an aqueous fluid containing a surface active agent and/or thickening agent and preferably a foam is produced during needling to aid in maintaining add-ons of needling fluid of at least 100%, e.g., 150% to 250%.

United States Patent 1191 1111 Smith, II 1 Oct. 21, 1975 15 FLUID AIDFOR NEEDLING 3,506,530 4/1970 Crosby 1, 161/154 x 3,549,475 12/1970Hcflcy ct a1. 161/154 X Invent Alexander $393,414 2/1974 Buff ct a1. .128/722 R ASSlgflEfil Flberwoven Corporation, 1,948,553 4/1971 Germany 1128/72] R [22] Filed: Oct. 3, 1973 [21] Appl NO: 403,058 PrimaryExaminer-Mervin Stcin Attorney, Agent, or FirmCushman, Darby & RelatedUS. Application Data c h [63] Continuation-impart 0f Ser No. 221,614,Jan. 28,

1972, Pat. N0. 3,817,820. 57 ABSTRACT [521 US. Cl H 28/722 R; 61,154,fin/55 A highly needled fabric is roduced by treating fabric, 1511111.01. D0411 18/00 hwmg dens of 8 [58] Field of Search H 28/4 72 2 R72 2 pounds per cubic foot, with a necdling fluid and then ll/kmneedling to increase the density, c.g., to at least 12 pounds per cubicfoot. The ncedling fluid is prcferably [56] References Cited an aqueousfluid containing a surface active agent and/0r thickening agent andprcferahly a foam is pr0 UNITED STATES PATENTS duced during needling toaid in maintaining add-ons of 33771564 611945 Lundgre" 23/4 R needlingfluid of at least c.g1, to 250% 2,908,064 10/1959 Lauterbach et a1161/154 X 3,235,935 2/1966 Daruwalla 28 72.2 R 39 Claims, 1 DrawingFigure 325 g 300 Q) 275 Q 250 225 200 (r /75 g L50 1 A25 /00 50 25 0 I ll L 1 l l 1 4L DE/VS/ 7' Y, POUNDS/CUB/C FOO 7' US. Patent Oct. 21, 1975505050505005 7 ZZZ .DF/VS/ 7'), POUNDS/CUB/C FOO 7' FLUID AID FORNEEDLING This is a continuation-in-part of copending application, Ser.No. 221,614, filed on January 28, 1972, now US. Pat. No. 3,817,820entitled NEEDLED TEXTILE FABRIC, the entire disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION The said copending application discloses atextile fabric which is composed of staple textile fibers that have beenformed into a batt and needled with a large number of needle punches persquare inch to produce a needled fabric of high bulk density and veryspecial physical properties. In one form of the invention, the highlyneedled textile fabric is finished to produce an artificial leather. Theproperties of the artifical leather, to a large measure, are the resultof the properties of the needled textile fabric per se, as opposed tothe finish placed thereon. In this process the batt of staple fibers isneedled through successive needling steps which progressively increasethe overall bulk density of the needled fabric. In a preferredembodiment, the batt of fibers is needled in FIBERWOVEN looms with eachside of the batt being needled in excess of 6,000 needle punches persquare inch to provide an overall bulk density of at least 12 lbs. percubic foot. As can be easily appreciated by those skilled in the art,this is a very large number of needle punches per square inch and thebulk density is considerably higher than that normally obtained byneedling alone. While the initial needling operations may proceed withthe looms being used in the normal and conventional manners, it has beenfound that as the bulk density and fiber entanglement progressivelyincreased, the fiber mobility in the needled fabric decreased to a pointwhere additional needling could not be practically performed. Whenfibers are substantially immobilized by high inter-fiber friction,further engagement by the barbs of the needles results in one or acombination of the following:

A. the substantially immobilized fibers exert sufficient force on theneedles to cause the needles to deflect and break;

B. the fibers so resist further movement that the barbs of the needlescut or break the engaged fibers; or

C. in the case of less positive barbs, the tensioned fibers slip out ofthe barbs of the needles and cause the needling process to besubstantially ineffective.

However, in order to accomplish the desired properties of the presentneedled fabric, especially the desired properties for artificialleather, it was necessary to achieve greater fiber entanglement andhigher needled densities. The methods which were discovered for allowingefficient needling to these greater fiber entanglements and higherneedled densities form a major feature of the invention although otherimportant features will be apparent hereinafter.

OBJECTS OF THE INVENTION It is therefore an object of the invention toprovide a method for producing a highly needled and intensely entangledfiber structure. It is a further object to provide a needling methodwhich allows exceedingly high numbers of needle punches per square inch,and the attendant greater fiber entanglement and higher bulk densitiesof a needled fabric, without substantial deterioration of the needledfabric or substantial harm to the needles of the needle loom performingthe needling operation. Other objects will be apparent from thefollowing disclosure and claims.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention,there is provided a method for producing a highly needled textile fabricby treating the textile fabric with a soaking amount of a wettingneedling fluid and needling the treated fabric in the presence of thesoaking amount of the wetting needling fluid to increase the overallbulk density of the needled fabric, e.g. to a density of at least I2lbs. per cubic foot. This process will provide a dense highly needledfabric with an intensely entangled fiber structure and withoutsubstantial deterioration of the fabric or needles.

The needling fluid preferably contains either a surface active agentand/or a thickening agent, such as aqueous solutions of a wetting agent,soap or thickening agent. The surface active agent or thickening agentmay produce any of the characteristic results thereof, e.g., foaming,lubricity, lowering of friction between fibers, etc. In a preferred formof the invention, the textile fabric is first needled until the overallbulk density of the fabric is at least approximately 8 lbs. per cubicfoot and the needled fabric is then treated with a needling fluid whichwill foam during a further needling operation and the foam aids inretaining the soaking amount of the needling fluid in the fabric duringthis further needling. The foaming may be a result of the surface activeagent and/or thickening agent or a separate foaming agent may be addedto the fluid. Conveniently the needling fluid is placed on the fabric bydip and nip (e.g. padding or the like) which provides addons of at leaste.g. to 200%. After the needling is completed, the needing fluid may beextracted and/or washed from the highly needled fabric and the fabricthereafter processed in any desired way.

DETAILED DESCRIPTION OF THE INVENTION While the present invention isespecially useful for fabrics prepared only by needling of staplefibers, it should be appreciated that the invention is applicable tofabrics which have been partly made by other processes, such as weaving,knitting, felting and stitching (e.g., "Malimo" techniques), and thenneedled, with or without the addition of staple fibers thereto, toproduce a needled structure having needled fibers closely entangled,especially at the face surface of the fabric, which presentsconsiderable resistance to further needle penetration. Thus, the termneedled fabric," as used herein is to be construed to included suchfabrics. The fibers of the textile fabric may be as desired and caninclude alone or in combination synthetic fibers such as thermoplastics,e.g. polyesters, nylon, acrylics, cellulosics, etc., and natural fibers,such as cotton, wool, hemp and flax. The denier and length of the staplefibers are not critical and can be any or a combination of theconventional deniers and lengths normally used with the needlingoperations. Thus, the deniers can be from as little as k to 54 denier orless to as great as 8 denier or more but the finer deniers arepreferred. The staple fibers may be single or multi-filament fibers.Thus, the fibers of the foregoing deniers may be composed of up to 10 to20 filaments. In these cases, each of the filaments will have individualdeniers generally proportionate to the total number of filaments andtotal denier, e.g., a ten filament. 1 denier staple fiber will have 101/10 denier filaments, etc. The fibers may have a length from as littleas A: inch or less to as great as 5 inches or more (either crimped ornoncrimped lengths).

It is preferred that the fabric is first needled until an overall bulkdensity of at least 8 lbs. per cubic foot is reached before the needlingfluid is applied to the fab ric. it has been determined that thisoverall bulk density, and corresponding needling density and fiberentanglement, is the approximate threshold density at which furtherneedling becomes difficult and encounters the problems noted above. Thisthreshold, however, can vary somewhat with the particular needled fabricand the fibers thereof, and may be from as little as 7 lbs. to as highas 11 lbs., but most often considerable needling difficulty isexperienced before fabric densities of lbs. per cubic foot are reached.At the lower of these densitites, i.e., 7 lbs. per cubic foot or less,the difficulty is not sufficiently serious as to require the needlingfluid of the present invention. Therefore, for partical application, thepresent needling fluid is not normally placed on the fabric until adensity of at least approximately 8 lbs. per cubic foot is reached butcertainly before a density of 10 lbs. per cubic foot is reached.However, if desired, the needling fluid can be placed on the fabricprior to reaching the 8 lbs. per cubic foot density. The essentialrequirement is that the needling fluid be present on the fabric, asdefined above, when further needling at densities above 8 lbs. per cubicfoot.

As noted above, the fabric may, in part, be made by methods other thanneedling, e.g., wovem. The woven structure (alone or with staple fibersadded thereon) is needled to the point where the needling fluid must beapplied to produce additional effective needling. in these cases, theunderlining woven structure may be considerably more dense than the 8lbs. per cubic foot density, where the needling fluid is required.However, the fibers entangled by needling (either added to the wovenstructure or pulled therefrom by the needles) will form a needledportion of the total structure which will have a needled density ofabout 8 lbs. per cubic foot. Accordingly, when considering fabircs otherthan needled fabrics, the calculation of the lower densities where theneedling fluid is to be added should be adjusted to account for thehigher, non-needled densities. Generally, this adjustment isproportionate to the relative weight of the structure which has thehigher nonneedled density. For example, if a woven fabric of 12 lbs. percubic foot has added thereto an equal weight of staple fibers and thenneedled, the density of the total structure at which the needling fluidwill be required will be higher than the aforementioned 8 lbs. per cubicfoot. Of course, the further needling of such composite fabrics willproduce correspondingly higher den sities than the 10 to 12 lbs. percubic foot, noted above.

Since the fabric must be further needled in the presence of the soakingamount of the wetting needling fluid, the needling fluid must bemaintained in the fabric throughout the further needling operation, i.e.the needling operation which increases the overall bulk density of thefabric to at least 10, especially at least 12, lbs. per cubic foot.Thus, the needling fluid must be of physical characteristics which willallow the needling fluid to be retained in the fabric during the furtherneedling in amounts sufficient to promote fiber mobility and furtherflber entanglement and assist and allow the fibers to be permanentlymoved by the needles, without placing deteriorating stresses on thefibers, i.e., stresses which would cause fiber breakage and/orsubstantial harm to the needles of the looms, e.g. cause breakage of theneedles. This foregoing described minimum amount of needling fluid whichmust be present during this further needling is referenced herein as thesoalc ing amount. This term may be better understood by reference to thefollowing example of the effects on needling with different amounts ofneedling fluid (water in this case) in the fabric during needling. Thus,with a needled fabric of about 8 lbs. per cubic foot density, nosubstantial effect of the water is noticed during needling with moisturecontents of up to about 8 to 10% water by weight. in other words, atthis moisture level, the fabric needles in the same essential manner asif it were dry. Accordingly, when it is attempted to obtain densitiesmuch above 8 lbs. per cubic foot at these moisture levels, thedifficulties hereinbefore noted are encountered. At moisture contentsbetween above about 8 and 10% and up to about 50% by weight of thefabric, the effect is to dramatically deteriorate the effectiveness ofneedling. At these moisture levels, needles rapidly break, the fabrictears and the needling is essentially ineffective. Thus, this range ofmoisture produces most undesired results. At moisture contents aboveabout 50% this undesired effect begins to mitigate and the needlingeffect with additional moisture contents up to about becomes quitesimilar to the needling effects of up to 810% moisture contents. Atmoisture contents at above about 100%, the effective needling andgreater fiber entanglement provided by the process of the presentinvention begins to occur. However, these effects are not obtained tothe degree desired for artificial leather at these lower add-ons andadd-ons, for this purpose, of at least equal to a soaking amount, arerequired. At higher fabric densities a soaking amount may be as low as100% but for lower fabric densities, a soaking amount will usually be atleast or as more fully explained hereinafter. Of course, the foregoingeffects are not abrupt but are transitional in nature and the exactpercentages in the foregoing regards will vary with the particularfabric, fabric density, fiber entanglement, needling fluid and needlingtechnique. However, the example illustrates the most unusual effectsproduced by fluids in the fabric during needling and the necessity of asoaking" amount of needling fluid, as defined hereinbefore.

Any fluid (liquid) which is stable under ordinary ambient conditions canbe utilized in the present process. However, as noted above, theneedling fluid must have physical characteristics which will allow theneedling fluid to be maintained in the fabric, during needling, insoaking amounts. The primary characteristic in this connection is thatthe needling fluid must simply be capable of sufficiently wetting (i.e.,adhering to) the fibers of the fabric, that the fluid can be relativelyuniformly dispersed on the fiber surfaces and entrained in the spacesbetween the fibers, as opposed to beading" on the surfaces of the fibersin the manner that mercury "beads on glass. This characteristic isdefined herein as wetting and the needling fluid as a wetting" needlingfluid. However, for commercial operations, it is a practical requirementthat the added needling fluid be retained on the fabric during at leastone pass through a needling machine, and the needling fluid should,preferably, have properties which assist in retaining the fluid in thefabric during this needling. The needling fluid should not only wet thefibers of the textile fabric but should be entrained in the structure asa foam or should at least be slow to drain from the structure because ofhigh viscosity and/or thixotropic character. Thus, the needling fluidmay contain surface active agents or thickening agents, foaming agentsor combinations thereof. However, if desired, the needling fluid can beapplied at sufficiently frequent intervals, or continuously, such thatduring the entire further needling operations a soaking amount can bemaintained in the fabric without the aid of foaming agents, thickeners,surface active agents, etc. The essential requirement is that a liquidbe sufficiently contained in the fabric that inter-fiber friction bereduced and fiber mobility be increased. Thus, the particular chemicalmake-up of the needling fluid is not critical so long as it is stable atneedling conditions and is not harmful to the fabric. The needling fluidmay be any of the conveniently available fluids such as alcohols,ethers, esters, aldehydes, hydrocarbons and halogenated hydrocarbons,but especially including lower alkanols, and lower alkanes. It ispreferred, for obvious and practical reasons, however, that an aqueousfluid be used, e.g., an aqueous solution or emulsion. Nevertheless, theneedling fluid may contain lower alkanols, e.g. methanol, ethanol,propanol, octanol, decanol and dodecanol, or higher fatty acid alcohols,e.g. lauryl alcohol, myristyl alcohol, palmityl alcohol and stearylalcohol or the corresponding alkanoic acids and higher fatty alkanes andacids. Corresponding polyfunctional compounds of the foregoing may alsobe used, for example, polyfunctional acids and alcohols, such asglycols, e.g. ethylene glycol, glycerol, sorbitol and pentraerythritolor the glycerides thereof. Also the inter-esters of the foregoing acidsand alcohols may be used.

Since the action of the needling fluid depends upon the ability of thefluid to be disposed on the surface of the fibers and entrained inspaces between the fibers, and, thereby reduce inter-fiber friction andincrease fiber mobility, and hence effective needling to produce greaterfiber entanglement, it is necessary that the needling fluid be awetting" fluid, as noted above. Accordingly, to assist in thisrequirement, the needling fluid preferably will contain a surface-activeagent. For aqueous needling fluids, many such surface-active agents areknown to the art, especially in connection with conventional fibers.Thus, any of the conventional textile wetting or scouring agents may be'used as the surface-active agent in the needling fluid. Among suitablewetting agents are anionic surface-active compounds having the formulaeR SOfA", R C,,I-l SOfA" and R O SOfA, where R is a C to C hydrocarbonresidue and A is an alkali metal or alkaline earth metal. Alternately,cationic compounds may be used which are acetates or simple salts oflongchain fatty acid amines, such as octadecyl ammonium chloride or thequarternary ammonium salts thereof with cations of the R N type.Alternately, nonionic compounds may be used, for example, a fatty acidesterified with a glycol, usually a lower aliphatic glycol of up to 30carbon atoms, such as a polyethylene glycol. Or, alkylated phenols ornaphtols, e.g. dodecylphenyl ether of hexaethylene glycol, may be used.The particular chemical compound or compounds of the wetting agent arenot at all critical and may be simply as desired, so long as they causethe fluid to substantially wet the fibers.

As noted above, commercial operations will usually include multiplepasses through needling areas of a needle loom. For example, aFIBERWOVEN needle loom has four sets of needle boards (four needleareas). These looms are most useful for the present needling operations.See U.S. Pat. Nos. 3,112,552; 3,090,099; 3,090,100; 3,112,549; 3,112,548and 3,132,406 for disclosures of suitable looms and needling techniques,which disclosures are incorporated herein by reference. Thus, for suchlooms it is not convenient to frequently re-apply needling fluid.Accordingly, it is preferable that the needling fluid be retained in thefabric for a reasonable period of time so that it may stay within thefiber structure during the passage of the structure through a needlingarea.

In a further preferred form of the invention, the needling fluidcontains a thickening agent to aid in retaining the needling fluid inthe fabric. Many such thickening agents for aqueous systems are known tothe art and include acrylates, modified starches, polyacrylic acid andpolyacrylamides, cellulosics, such as carboxy methyl cellulose,hydroxyethyl cellulose, methyl and hydroxypropyl methyl cellulose,polyvinyl acetate and alcohol, water soluble vinyls, includingpolyvinylpyrrolidone, polyethylene oxide, polyethylenimine, natural andsynthetic gums, such as alginates, gum arabic, guar, karaya, locust beanand tragacanth. The particular thickening agent is not critical and maybe chosen as desired but it is preferable to select an agent which iseasy to remove after the needling process and which provides asubstantial increase in viscosity for a given quantity added to theneedling fluid, e.g. a needling fluid viscosity of at least 2 cp. or 3cp. (Brookfield CPS-10 spindle, 12-60 RPM). However, higher viscositiesare preferred, especially when the needling fluid does not substantiallyfoam, as discussed in more detail hereinafter. Thus, viscosities of atleast 4 to 10 cps are preferred and the viscosity may be as high as 50to cps.

It should be understood, however, that the same agent may function asboth the surface-active agent and the thickening agent. In this regard,the surfaceactive agent may simply be contained in the needling fluid insufficiently high concentration so as to also provide thickening of theneedling fluid. Alternately, an aqueous needling fluid may be thickenedby the suspension of an immiscible liquid, i.e., an emulsion of ahydrocarbon and an emulsifier in an aqueous continuous phase. Forexample, a 50/50 volume ratio of water and naptha cut solvent (such asVarsol) can be emulsified with a fatty acid soap to produce a thickenedemulsion.

in a further preferred form of the invention, the needling fluid willhave a foaming agent therein so that the action of the needles on thefabric during the further needling will cause the needling fluid to foamand thereby the needling fluid will be entrained in the fiber structureand thus be retained in the fabric during the entire further needlingoperation. Here again, the foaming agent may be the same or different aseither the surface-active agent or the thickening agent, as discussedabove. However, many foaming agents, the same as the surface-activeagents or different therefrom, are known in the art and include fattyacid soaps,

as discussed above, protein hydrolyzates, longchain florinated ethersand thio ethers. The foaming is more efficiently performed by soaps, asopposed to detergents, and fatty acid soaps are thus preferred. Thesesoaps also give reasonably good wetting, especially the amine coconutfat soaps. Here again, the particular chemical composition of thefoaming agent is not critical.

As can be appreciated, the surface active agent, thickening agent andfoaming agent (if different from the foregoing) may be contained in theneedling fluid in widely varying amounts and the particularconcentration thereof is not critical so long as the above functions areprovided. However, generally speaking each may be contained in theneedling fluid in amounts ofas low as 0.01% to as high as 20% by weight,but usually between 0.1% and 15%, eg. between 0.5% to 1.5% and to 10%.

The needling fluid may be conveniently disposed on the fabric by simplysoaking the fabric in the needling fluid. For example, the fabric may bedipped in the needling fluid and then passed through nip rolls to removeexcess needling fluid. Alternately, the fabric may be sprayed orotherwise treated with the needling fluid. The dip and nip are, however,most convenient and will supply a soaking amount of needling fluid topromote fiber mobility and is the preferred method. For example, withmost fabrics and fibers, this method will result in add-ons whichessentially saturate the fabric. The term add-on," as used in thisspecification and claims, is defined as the weight increase of thetreated fabric caused by the addition of needling fluid as compared withthe weight of the untreated fabric. Thus, for example, if one pound ofdry fabric contained 1% pounds of needling fluid, the add-on would be150%. Also, as can be appreciated, the number of inter-fiber contactpoints (interstices) and the space between fibers will vary with thedegree of fiber entanglement and the fabric density; thus, the amount offluid which must be present to obtain further effective needling andfurther intensity of fiber entanglement depends on the density of thefiber structure, as illustrated in Example 1 hereinafter. Generally, thedesired minimum quantity of needling fluid which must be presentdecreases as the fabric density increases.

While minimum add-ons of needling fluid are required for effectivefurther needling, on the other hand, the add-ons of the needling fluidshould not be excessive, since the higher add-ons are more difficult tohandle and maintain in the fabric, especially in commercial size needlelooms. Further, from a practical point of view, with densities in thepresent ranges, it is difiicult to obtain add-ons substantially inexcess of 275%. In any case, add-ons in excess of 300% are notpreferred. With the proper quantity of needling fluid present in thefiber structure further needling may be performed so that the resultingfabric can have intense fiber entanglement as measured by fiberreversals and curvature and at the same time can have overall bulkdensities in excess of 13 or 14 lbs. per cubic foot, e.g. 15 lbs. percubic foot. However, with sufficient needling, bulk densities of as highas 16 to 18 or even 20 to 21 lbs. per cubic foot can be obtained (alldensities calculated on a non-woven needled structure or the needledportion of a composite structure.

After the further needling is accomplished, the needling fluid isextracted, eg by vacuum for recovery and reuse, and/or simply washedfrom the fabric by any of the conventional scouring or washingtechniques and the fabric may be dried or otherwise treated as desired.

For purposes of the present specification, the overall bulk densityreferenced herein is defined as the weight per volume of the fabric,wherein the thickness of a section of fabric is determined for thevolume calculation by pressing a 1.129 inch diameter presser foot (1square inch) against a section of fabric held on a 2 inch diameter anvilwhere the presser foot is loaded with 10 ounces of weight, and measuringthe thickness of the section. This is a standard means in the art ofdetermining the overall bulk density of felt-like fabrics. (For moredetails see ASTM test D-46l-67). It should be appreciated, however, thatthe bulk density of primary importance is the bulk density of anyportion of a fabric through which the needles must pass. For example,where the fabric has a bulk density gradient, as in the aforenotedparent application, the overall bulk density of the total fabric couldbe less than the bulk density of the top surface of the fabric. Thus forpurposes of the present specification and claims, the bulk density beingreferenced is any finite bulk density through which the needles mustpass.

While the invention will be illustrated in connection with a needledtextile fabric according to the process of the aforenoted parentapplication, it should be understood that the invention is notrestricted thereto and is fully applicable to the breadth of theforegoing disclosure.

EXAMPLE 1 According to Example 1 of the aforenoted parent application, abatt of staple polyester fibers (1% to 5 denier and 1% to 3 inchescrimped length) was needled in three FIBERWOVEN looms, the first andsecond looms with l-l6-4C needles therein (l-barb-l6 mil triangularblade-4 mil barb depth) and the third with ll6-3C needles. A first layerof fibers constituted by 3 ounces per square yard of 1% denier and 1%inch length polyester staple fibers was carded onto the batt and then asecond layer of the same fibers, except fiveeighths inch in length, wascarded on the first layer. The batt was needled in the same manner asthe previous needling step and the density of the resulting needledfabric was approximately 8 lbs. per cubic foot. The total number ofneedle punches to each side of the fabric to accomplish this density wasapproximately 4,500 needle punches per square inch.

The so-needled fabric was immersed in a water solution of a methylaminesalt of coconut fatty acids (PEN- ETRANT GWX, Woonsocket Color andChemical Co.). The concentration of the amine salt in the water was 6%by weight. This amine salt functioned as a surface active agent,thickening agent and foaming agent. After the fabric had becomesaturated with the needling fluid, it was removed from the fluid andpassed through the nip of two lightly pressed counter-rotating smoothrolls which expressed excess needling fluid from the fabric and producedan add-on of between and 200%. The wetted fabric was then needled in afurther FIBERWOVEN loom having the same needles as noted above until thedensity of the needled fabric was approximately 13 lbs. per cubic foot.The total number of needle punches in this further'needling operationwas slightly in excess of 6,500 needle punches per square inch of eachside of the fabric. Thus, the

total number of needle punches to produce the final overall bulk densityin this example was in excess of 10,000 needle punches per square inchon each side of the needled fabric or a total number of needle punchesper square inch in excess of 22,000.

The foregoing overall bulk density was obtained without any significantdeterioration of the fabric during the further needling operation andwithout any signiflcant damage to the needles of the FIBERWOVEN loom.The fabric had the resilient characteristics of an intensely andrandomly entangled fiber structure.

It should be noted that during the further needling operation theneedling fluid foamed and formed a lather throughout and on top of thefabric, which foam remained during the further needling operation. Theadd-ons of the needling fluid did not drop below 100% throughout theentire further needling operation and the add-ons, mainly, were about150% through the entire further needling operation.

As a comparison with the foregoing, the same process was repeated,except that the needling fluid added to the 8 lbs. per cubic foot fabricwas water alone. After only about a thousand additional needle punchesper square inch on each side of the fabric, the water had significantlydrained from the fabric and needling became ineffective. With continuedneedling, additional water drained and dried from the fabric and theaddons of water fell well below a soaking amount needle breadage andfabric deterioration began to occur.

As noted above, the relationship between the density of the fabric to befurther needled and the add-ons required to assist in effective furtherneedling and further intensity of fiber entanglement forms a criticalbasis of the present invention, i.e., there must be present a soakingamount. However, for precise control of any particular fabric and anyparticular fibers used therein, this relationship can be specificallydetermined for fabric of different densities upon which needlingcommences, as well as the add-ons required during needling where thedensity is increasing. Thus, for a series of densities and a series ofadd-ons, it can be'determined where substantial deterioration of thefabric and sub stantial harm to the needles occur and where effectiveneedling and further intensity of fiber entanglement take place. By sucha series of experiments, one can determine the relationship betweendensity and add-ons for any particular fabric density prior to or duringneedling.

The Figure is constructed for a fabric of a nature described in theExample. As can be seen, there is a relationship between the density anthe add-o'ns useful in increasing fiber entanglement and bulk densityduring the further needling operation. At above 8 pounds per cubic footdensity, the minimum add-on (soaking amount) for effective needling andfurther intense entanglement of fibers is plotted, along with themaximum practical add-on that can be conveniently used. Any add-ongreater than the minimum is satisfactory. The preferred add-on is alsoshown. As can be seen from the Figure, the soaking amount of theneedling fluid varied inversely with the density of the fabric. Thus,the soaking amount decreases as needling proceeds and the density of thefurther needled fabric increased. For the preferred needling fluids,i.e., aqueous solutions of surface-active agents, thickeners, foamingagents, etc., a fabric, initially provided with at least a soakingamount of needling fluid appropriate for the initial density of thefabric and promptly needled, will retain a soaking amount during thefurther needling, since the soaking amount decreases with increasedfabric density and thereby compensates for mechanical loss of needlingfluid during the further needling. On the other hand, if the furtherneedling is delayd or interrupted, it will be necessary to re-apply thesame needling fluid to restore at least a soaking amount to the fabricbefore needling commences.

EXAMPLE 2 A needled batt was prepared according to the process ofExample 1 having a bulk density of 7% lbs. per cubic foot. The batt wastreated with a 0.13% (by weight) water solution of locust bean gum(Polygum- 260, Polymer Industries, Inc.). The treated batt was thenneedled essentially in the same manner as that according to the furtherprocedure of Example 1 and the resulting needled product has a bulkdensity of 12 lbs. per cubic foot and the other physical properties weresimilar to that of the product of Example 1.

The locust bean gum functioned, essentially only, as a thickening agentand no substantial foaming took place. The locust bean gum did not,however, sufficiently change the wetting" properties of the water so asto render the solution a non-wetting fluid.

It should be understood, however, that while the different additives,e.g. surface-active agent, foaming agent, thickener, etc., will allowthe needling to proceed to higher densities and produce similarproducts, the products resulting from the different needling fluids arenot always identical. The different needling fluids can produce somewhatdifferent fiber entanglements and, for this reason, one additive may bechosen over another, or combinations thereof, for making specialproducts.

What is claimed is:

1. A method for producing a highly needled textile fabric comprising:

1. first needling a textile fabric;

2. treating the needled fabric with a soaking amount of a wettingneedling fluid and until add-ons of at least are obtained; and

3. further needling the treated fabric while maintaining the soakingamount and the at least 100% add ons of the wetting needling fluid toincrease the overall bulk density of the needled fabric.

2. The method of claim 1 wherein the treated fabric is needled to adensity of at least 10 lbs. per cubic foot.

3. The method of claim 2 wherein the treated fabric is needled to adensity of at least 12 lbs. per cubic foot.

4. The method of claim 3 wherein the needling fluid is an aqueous fluidcontaining a surfaceactive agent or thickening agent or combinationsthereof.

5. The method of claim 4 wherein the needling fluid contains a foamingagent.

6. The method of claim 1 wherein the fabric is dipped into the needlingfluid and then passed through nip rolls to remove excess fluid.

7. The method of claim 1 wherein the fabric is saturated with theneedling fluid.

8. The method of claim 1 wherein the add-ons maintained during thefurther needling are at least and less than 300%.

9. The method of claim 8 wherein the add-ons maintained during thefurther needling are between about and 250%.

l0. The method of claim 1 wherein the said density of the first needledfabric prior to treating with the needling fluid is at least 8 lbs. percubic foot.

11. The method of claim 10 wherein the density of the first needledfabric prior to treating with the needling fluid is less than 10 lbs.per cubic foot.

12. The method of claim 1 wherein the needling fluid is an aqueousfluid.

13. The method of claim 12 wherein the needling fluid is an aqueousfluid containing a surface-active agent or thickening agent orcombinations thereof.

14. The method of claim 13 wherein the aqueous fluid contains a surfaceactive agent.

15. The method of claim 13 wherein the aqueous fluid contains athickening agent.

16. The method of claim 14 wherein the aqueous fluid contains a foamingagent.

17. The method of claim 16 wherein the aqueous fluid foams during thefurthei needling.

18. The method of claim 1 wherein the needling fluid is washed from thefurther needled fabric after the further needling is completed.

19. The method of claim 1 wherein the treated fabric is needled bymutiple passes through at least one needling zone.

20. A method for producing a highly needled textile fabric comprising:

1. first needling a textile fabric until the overall bulk density of thefabric is at least approximately 7 lbs. per cubic foot;

2. treating the needled fabric with a soaking amount of a wettingneedling fluid to increase the overall bulk density of the needledfabric to at least 10 lbs. per cubic foot;

whereby the fabric is further needled to produce an intensely andrandomly entangled fiber structure and without substantial deteriorationof the fibers of the fabric.

21. The method of claim 20 wherein the treated fabtie is needled to adensity of at least 12 lbs. per cubic foot.

22. The method of claim 21 wherein the treated fabric is needled to adensity of at least 14 lbs. per cubic foot.

23. The method of claim 20 wherein the needling fluid is an aqueousfluid containing a surface-active agent or thickening agent orcombinations thereof.

24. The method of claim 23 wherein the needling fluid contains a foamingagent.

25. The method of claim 20 wherein the fabric is dipped into theneedling fluid and then passed through nip rolls to remove excess fluid.

26. The method of claim 20 wherein the fabric is saturated with theneedling fluid.

27. The method of claim 20 wherein the fabric is treated by the needlingfluid until add-ons of at least are obtained and add-ons of at least100% are maintained during the further needling.

28. The method of claim 27 wherein the add-ons maintained during thefurther needling are at least and less than 300%.

29. The method of claim 28 wherein the add-ons maintained during thefurther needling are between about and 250%.

30. The method of claim 27 wherein the said density of the first needledfabric is less than 10 lbs. per cubic foot.

31. The method of claim 30 wherein the density of the further needledfabric is at least 12 lbs. per cubic foot.

32. The method of claim 20 wherein the needling fluid is an aqueousfluid.

33. The method of claim 32 wherein the needling fluid is an aqueousfluid containing a surface-active agent or thickening agent orcombinations thereof.

34. The method of claim 33 wherein the aqueous fluid contains a surfaceactive agent.

35. The method of claim 33 wherein the aqueous fluid contains athickening agent.

36. The method of claim 34 wherein the aqueous fluid contains a foamingagent.

37. The method of claim 36 wherein the aqueous fluid foams during thefurther needling.

38. The method of claim 20 wherein the needling fluid is extracted orwashed from the further needled fabric after the further needling iscompleted.

39. The method of claim 20 wherein the treated fabric is needled bymiltiple passes through at least one needling zone.

* i i i

1. A method for producing a highly needled textile fabric comprising: 1.first needling a textile fabric;
 2. treating the needled fabric with asoaking amount of a wetting needling fluid and until add-ons of at least100% are obtained; and
 3. further needling the treated fabric whilemaintaining the soaking amount and the at least 100% add-ons of thewetting needling fluid to increase the overall bulk density of theneedled fabric.
 2. treating the needled fabric with a soaking amount ofa wetting needling fluid and until add-ons of at least 100% areobtained; and
 2. The method of claim 1 wherein the treated fabrIc isneedled to a density of at least 10 lbs. per cubic foot.
 2. treating theneedled fabric with a soaking amount of a wetting needling fluid toincrease the overall bulk density of the needled fabric to at least 10lbs. per cubic foot; whereby the fabric is further needled to produce anintensely and randomly entangled fiber structure and without substantialdeterioration of the fibers of the fabric.
 3. further needling thetreated fabric while maintaining the soaking amount and the at least100% add-ons of the wetting needling fluid to increase the overall bulkdensity of the needled fabric.
 3. The method of claim 2 wherein thetreated fabric is needled to a density of at least 12 lbs. per cubicfoot.
 4. The method of claim 3 wherein the needling fluid is an aqueousfluid containing a surface-active agent or thickening agent orcombinations thereof.
 5. The method of claim 4 wherein the needlingfluid contains a foaming agent.
 6. The method of claim 1 wherein thefabric is dipped into the needling fluid and then passed through niprolls to remove excess fluid.
 7. The method of claim 1 wherein thefabric is saturated with the needling fluid.
 8. The method of claim 1wherein the add-ons maintained during the further needling are at least125% and less than 300%.
 9. The method of claim 8 wherein the add-onsmaintained during the further needling are between about 150% and 250%.10. The method of claim 1 wherein the said density of the first needledfabric prior to treating with the needling fluid is at least 8 lbs. percubic foot.
 11. The method of claim 10 wherein the density of the firstneedled fabric prior to treating with the needling fluid is less than 10lbs. per cubic foot.
 12. The method of claim 1 wherein the needlingfluid is an aqueous fluid.
 13. The method of claim 12 wherein theneedling fluid is an aqueous fluid containing a surface-active agent orthickening agent or combinations thereof.
 14. The method of claim 13wherein the aqueous fluid contains a surface active agent.
 15. Themethod of claim 13 wherein the aqueous fluid contains a thickeningagent.
 16. The method of claim 14 wherein the aqueous fluid contains afoaming agent.
 17. The method of claim 16 wherein the aqueous fluidfoams during the further needling.
 18. The method of claim 1 wherein theneedling fluid is washed from the further needled fabric after thefurther needling is completed.
 19. The method of claim 1 wherein thetreated fabric is needled by mutiple passes through at least oneneedling zone.
 20. A method for producing a highly needled textilefabric comprising:
 21. The method of claim 20 wherein the treated fabricis needled to a density of at least 12 lbs. per cubic foot.
 22. Themethod of claim 21 wherein the treated fabric is needled to a density ofat least 14 lbs. per cubic foot.
 23. The method of claim 20 wherein theneedling fluid is an aqueous fluid containing a surface-active agent orthickening agent or combinations thereof.
 24. The method of claim 23wherein the needling fluid contains a foaming agent.
 25. The method ofclaim 20 wherein the fabric is dipped into the needling fluid and thenpassed through nip rolls to remove excess fluid.
 26. The method of claim20 wherein the fabric is saturated with the needling fluid.
 27. Themethod of claim 20 wherein the fabric is treated by the needling fluiduntil add-ons of at least 100% are obtained and add-ons of at least 100%are maintained during the further needling.
 28. The method of claim 27wherein the add-ons maintained during the further needling are at least125% and less than 300%.
 29. The method of claim 28 wherein the add-onsmaintained during the further needling are between about 150% and 250%.30. The method of claim 27 wherein the said density of the first needledfabric is less than 10 lbs. per cubic foot.
 31. The method of claim 30wherein the density of the further needled fabric is at least 12 lbs.per cubic foot.
 32. The method of claim 20 wherein the needling fluid isan aqueous fluid.
 33. The method of claim 32 wherein the needling fluidis an aqueous fluid containing a surface-active agent or thickeningagent or combinations thereof.
 34. The method of claim 33 wherein theaqueous fluid contains a surface active agent.
 35. The method of claim33 wherein the aqueous fluid contains a thickening agent.
 36. The methodof claim 34 wherein the aqueous fluid contains a foaming agent.
 37. Themethod of claim 36 wherein the aqueous fluid foams during the furtherneedling.
 38. The method of claim 20 wherein the needling fluid isextracted or washed from the further needled fabric after the furtherneedling is completed.
 39. The method of claim 20 wherein the treatedfabric is needled by miltiple passes through at least one needling zone.